The present invention relates generally to the medical arts and more particularly to an improved means for guiding various catheters, cannulas, scopes, and the like during insertion and/or advancement thereof into various anatomical passages, tracts, cavities, vessels, and/or other structures of the body.
The prior art includes numerous catheters, cannulae, and tubular endoscopic devices having distal ends which are adapted for steering or manipulation. Examples of such devices are set forth in U.S. Pat. Nos. 3,890,977 (Wilson), 4,033,331 (Guss et al.), 4,543,090 (McCoy), 4,601,705 (McCoy), and 4,758,222 (McCoy).
Notably, U.S. Pat. Nos. 4,543,090, 4,601,705, and 4,758,222 describe a catheter having a steerable and/or bendable distal end. Such catheter incorporates known temperature-activated memory elements made of materials such as titanium-nickel alloys having heat-activated "mechanical memory". Each such temperature-activated memory element has a first "preset" shape and a second "straightened" shape. Such temperature-activated memory elements are initially disposed within the catheter in their straightened configuration. However, when electrically heated to a predetermined transitional temperature, the memory elements will undergo bending, thereby effecting the desired bending of the distal end of the catheter. A control system is provided for controlling current flow to the temperature-activated memory elements Such control systems include a power supply source (AC or DC) in conjunction with a controlling or steering means (e.g. a "joy stick", tactile membrane switch or ball controller) for triggering selective heating, and hence selective directional bending, of the various temperature-activated memory elements disposed within the distal end of the catheter.
Although such steerable/bendable catheters and scopes of the prior art may indeed incorporate means for bending or directing the distal portions thereof, many of these prior art devices are expensive to manufacture and/or less than optimal for certain medical applications. Accordingly, there remains a need in the art for a practically applicable, steerable or directable cannula, catheter or scope which may be inexpensively and reproduceably manufactured.